Artificial dentures and process of preparing



ARTIFICIAL DENTURES AND PROCESS OF PREPARING Wilhelm Becker, Koln-Stammheim, and Dieter Steuer,

Frankfurt am Main, Germany, assignors to Farbenfabriken Bayer Aktieugesellschaft, Leverkusen, Germany, a corporation of Germany No Drawing. Application May 26, 1954 Serial No. 432,605

. priority, application Germany May 29, 1953 6 Claims. (Cl. 32-4) The present invention relates to artificial dentures with soft cushion linings and particularly to a process of making such dentures and to providing satisfactory attachment between the soft cushion lining and the denture base material. I

Artificial dentures prepared from methyl methacrylate havethe advantage of physiological and chemical indifference as-well as of good mechanical properties. According to aknown process these dentures may be prepared by the following method: Mixtures of monomeric, liquid, polymerizable methacrylic acid derivatives and polymers,for instance polymeric methyl methaerylate, together with suitablecata-= lysts, for instance organic peroxides, are packed into a conventional denture mold and hardened therein by polymerization with'the. application of pressure and heat. It is of advantage --to provide the surface of the denture which is permanently in contact with the tissue of-the mouthwith a'lining of a soft material which, due

to its resilience, does notirritate the tissue of the mouth? Such a lining gives the dentures an accurate. fit in the mouth and improves the adhesion of the-dentures to the tissue. a v a The tissue. of the mouth with which dentures are permanentlyincontact consists of mucous membrane and includes the gums. .For convenience, the side of the denture making permanent contact with the tissue of the mouth is referred to herein as the tissue side.

It-is known to prepare soft cushion linings on dentures from polymers: containing plasticizers. Because of the disadvantage of becoming hard'with use.

. It i'san' object of this invention to provide artificial dentures'having soft cushion linings which are durable and do not shrink, separate or 'peel, and which do not become hard and distorted with use.

It is another objectofi the invention to provides. process for making artificial dentures having soft cushion linings which are durable and do not shrink, separate or peel,and which do notbecome hard and distorted with use. a 1

It is a further object of the invention to provide a process of economically. and conveniently producing soft cushion lining materials in. a convenientform for making improved artificial dentures.

It is still a further object of the invention to provide suitable materials for producing strong chemical union between the soft cushion lining material and the hard denture base material.

Still further objects will become apparent as the following description proceeds.

In accordance with the present invention it has now been found that improved dentures with soft cushion linings can be prepared in a technically simple process by utilizing for the lining a soft and non-hardening material comprising a copolymer of acrylates or methacrylates together with butadiene. It has proved to be especially 2,874,467 Patented Feb. 24, 1959 ice advantageous to incorporate with these copolymers antioxidants such as they are known from rubber chemistry. of course, these antioxidants must be non-toxic and shall preferably not give rise to discoloration.

The application of the afore-said copolymers on artificial dentures to form soft cushion lining thereon can be accomplished by most various methods, for instance by leaving a recess ,on the tissue side of the denture or cutting away the portion of the denture to be replaced with the soft and non-hardening material, and applying this material to this place while effecting strong union between the softmaterial and the denture with the aid of an autopolymerizing plastic.

Suitable autopolymerizing plastics for this purpose are especially mixtures of polymers having a basis of methyl methacrylate with polymerizable liquid monomers which polymerize by addition of redox systems volatility.'.of the plasticizers these polymers show the.

within a comparatively short time without the application of higher temperatures.

Another method of preparing dentures with soft cushion linings consists in applying the soft and non-hardening material to a mixture of polymeric and liquid polymerizable compoundsand effecting solidification by polymerizing in a conventional denture mold with the application of pressure and heat (see copending application.

Ser. No. 235,096, filed July 3, 1951, by Hermann Schnell and Wilhelm Becker). According to this method it has proved to be preferable to employ anexcess of compounds giving off oxygen and/or reducing agents, es-

pecially in the case of a soft material containing stabilizers. r

'Ihe copolymers of acrylates or methacrylates together with butadiene can. be produced by the most various methods. Besides :acrylates or methacrylates, other polymeri'zable vinyl compounds ordivinyl compounds may be employed. The term .butadiene as herein used is intended to refer to butadiene as such, its homologues and derivatives. Examples of stabilizers are phenyl flnaphthylamine and the reaction products of substituted phenols and formaldehyde. ing to the invention are compoundsgiving off oxygen, for instance benzoylperoxide. As reducing substances there maybe used amines or organic sulfinic acids, salts or derivatives thereof. i

The soft and non-hardening materials obtained by the herein described process retain their soft consistency and are further distinguished by high tensile strength It was surprising that these polymers providean excellent adhesion with dentures prepared for instance from methyl methacrylate. This could not be foreseen since, as is known, the production of a' proper chemical union between non-hardening foils of natural rubber or polymers containing a high proportion oflbutadieue' with dentures of -plastic material involves 'difficulties'. Previously, these materials could often be attached to one another by mechanical anchorage only. A particularly high technical advantage brought about by the present invention resides in the factthat polymerization of the denture base ma terials is not delayed bypolymerization-inhibiting stabilizers incorporated in the soft material. This is accomplished especially by the application of an excess of catalysts or by addition of reducing substances. The catalysts or reducing substances can be added either by dissolving them in the monomeric component of the denture base material or applying them to the surface of foils prepared from the herein described copolymers in the form of a lacquer or varnish coating, for instance by brushing. It is also feasible to incorporate the activators and reducing agents into the foils directly.

The soft cushion linings prepared according to the invention on dentures are durable and do not separate Suitable activators accord-.

Peel they 519.1 9! shrinhbr breaths fou and do not become hard or distorted wiih use.

The present invention is further illustrated by the folin examp es i hout be ng re ict d the et Br nd .1 a V. 15 grams of polymethyl methacrylate and 0.015 gram of benzoyl peroxide are soaked with cc. of monomeric methyl methacrylate wherein 0.015 gram of the'morphqline salt of o-ethylene benzene sulfinic acid are dissolved and left standing in a covered vessel to form a dough. The dough thus obtained is packed into a conventional ental a k a d are-s ped nd pr ssu h als ee f cel phan te pos d e een t e u es of he ask an he mat ria il e flask is op ned and a suflicient portion of the dough of monomeric and polymeric methyl m thac y at i remo ed t pe mit the ppl cation f a foi m de f om a copolyme of 49% fbu adi ne d 60% of m thyl met aa y te. i h copolym r 9ona ns o 2-2'-me hylen -bi m thylryclohexy 'phenol) as stabilizer. After finally closing under pressure the flask is heated in the water-bath to 100 C. for 30 minutes and the dough hardened by polymerization.

After cooling the flask is opened and a denture'removedwhich is provided on the tissue side with a soft and nonhardeninglining that is attached to the denture by a proper chemical union and distinguished by high tensile strength and excellent stability to mouth fluids;

Example 2 terial to be applied thereto. Thereupon a mixture is prepared from 4 grams of a copolymer consisting of 6% of aerylonitrile and 94% of methyl methacrylate, 0.24 gram of benzoyl peroxide with 2 grams of monomeric methyl methacrylate and 0.1 gram of dimethylrp-toluidine. The mixture is brushed to an appropriately sized foil of a copolymer of 35% of butadiene and 65% of methyl methacrylate stabilized as described in Example 1 and the foil thus coated is slightly heated above a flame and placed in position on the denture with the application of pressure. The flask is closed and left standing under pressure for about 20 minutes. The flask is then opened and a denture removed which is provided on the tissue side with a strongly adhering soft and non-hardeninglin ing which is distinguished by excellent t'ensilestrength and stability to mouth fluids.

Example 3 Foils of a copolymer eonsisting of 30% of butadiene, 60% of methylmethacrylate, and 10% of butyl acrylate, which is stabilized with the reaction product of p-cresol and formaldehyde, is placed into a denture flask. The side of the foil which does not face the plaster of Paris is coated with tertiary butyl hydroperoxide and the flask is packed with a dough of grams of a copolymer consisting of 99% of methyl methacrylate and 1% of ethyl acrylate and 5 grams of monomeric methyl methacrylate,

wherein 9. 15 gram of benzoyl perox de is i S IYF LiQ the manner common to dental technology. After closing the flask the latter is heated in an oven to C. for 8 hours and to C. for another hour and the dough solidified by polymerization. After cooling the flask is opened and the denture removed. The denture thus ob tained is provided on the tissue .side with a soft and nonhardening lining attached to the denture in strong chemical union and distinguished by excellent tensile strength and stability to mouth fluids.

We claim:

1. An artificial denture comprising a hard, artificial base material and a soft cushion lining integrally attached to'the tissue side of said base material, said lining consisting essentially of a copolymer of (1) a member of the group consisting 'sr' o1 n'1eri'zab1e vinyl anddivinyl compounds and (2) hutadiene.

2. An artificial'denture comprising a hard, artificial base material and a soft cushion lining integrally attached to the tissue si e of sai b se ma er al, said linin consisting essentially of a-copolyrner of (1), an acrylate and (2) butadiene.

3. A process of preparing artificial dentures having soft cushion linings which comprises applying, to the tissue side of a hard, artificial base material, a soft cushion lining consisting of a copolymer of (1) a member of the group consisting of polymerizable vinyl and divinyl compounds and (2) butadiene by means of a polymerizable composition comprising (1) a methacrylate polymer, (2) a polymerizable liquid, ethylenically unsaturated monomeric compound, and (3) a polymerization catalyst, and hardening by polymerization reaction to produce a proper chemical union between the two layers.

'4. The process of claim 3, wherein the polymerization reaction is effected with the application of pressure and heat.

5. The process of claim 3, wherein the copolymer of the group consisting of vinyl and divinyl compounds is an acrylate.

6. A process of preparing an artificial denture having a soft cushion lining comprising the steps of packing'an acrylic resin into one partof a two part denture mold, placing over said resin 8. thin sheet of a mixture of (1) a' polymer of methyl methacrylate, (2) a polymerizable liquid monomeric compound selected from the group consisting of esters of acrylic acid and methacrylieacid, and (3) a polymerization catalyst, placing over said sheet at'the open face of the mold a soft cushion lining eon sisting essentially of a copolymer of acrylates and 'bfuta diene, closing the mold to shape the'acrylic resin and the lining and hardening the dough by the polymerization reaction to produce a proper chemical union between the two layers.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN ARTIFICAL DENTURE COMPRISING A HARD, ARTIFICIAL BASE MATERIAL AND A SOFT CUSHION LINING INATEGRALLY ATTACHED TO THE TISSUE SIDE OF SAID BASE MATERIAL, SAID LINING CONSISTING ESSENTIALLY OF A COPOLYMER OF (1) A MEMBER OF THE GROUP CONSISTING OF POLYMERIZABLE VINYL AND DIVINYL COMPOUNDS AND (2) BUTADIENE. 